Hydraulic gun barrel brake mechanism



' March w, 1942.

B. P. JOYCE 2,275,632

HYDRAULIC GUN BARREL BRAKE MECHANISM Filed June 13, 1940 5 Sheets-Sheet l arch 10, 1942.

B. P. JOYCE HYDRAULIC GUN BARREL BRAKE MECHANISM Filed June 15, 1940 5 Sheets-Sheet -2 IIIIIIIIII IIIIIII'] v 1 il v f;

3 Sheets-Sheet 3 mm mm \W .QN

E C Y Q J P B Filed June 13, 1940 HYDRAULIC GUN BARREL BRAKE MECHANISM Patented Mar. 10, 1942 HYDRAULIC GUN BARREL BRAKE MECHANISM 13 Claims.

The invention relates to a new and improved brake mechanism for controlling the recoil and counter-recoil of gun barrels.

The principal object of the invention is to provide an improved counter-recoil controlling means so that the time required for counterrecoil is the same when the gun is fired at all angles of elevation and depression.

When the recoiling parts of a cannon are relatively heavy and the gun is fired at say 80 or 90 elevation, considerable power is required from the recuperator to lift the recoiling parts and bring the gun back into battery position. When the gun is fired, in a substantially horizontal position and the recuperator does not have to lift the recoiling parts, said recuperator has an excess of power which causes the gun to return to battery with a severe shock unless it is properly controlled. The present invention provides such control by throttling liquid through an orifice as the gun returns to battery, and the area of the orifice is increased as the gun is elevated and so frees more and more of the power of the recuperator, to be utilized in lifting the recoiling parts, during the counter-recoil thereof.

When a cannon is mounted on an aircraft and designed to fire in depression as well as in elevation, the counter-recoil orifice must be arranged to permit the full effect of the brake means to act to resist the tendency of the recoiling parts to return to battery by gravity, and

' the present invention provides for this also.

When recoiling automatic guns are fired from the ground, it has been found that if they possess a constant counter-recoil orifice, the rate of fire is materially greater when fired at substantially horizontal, than when fired at the higher elevations. In an automatic gun, it is desired to have as high a rate of fire as is practicable, especially when firing against aircraft; and the present invention, by providing a counter-recoil orifice which is automatically adjusted to the elevation of the gun, insures that the rate of fire of the gun will be the same when it is fired at elevation, as when it is fired at horizontal.

The ever increasing sizes of automatic cannon now being used on aircraft require that they have a recoil brake to cushion the shock of firing against the relatively delicate aircraft structure. These aircraft cannon are so designed that they have the highest possible rate of fire. A gravitycontrolled valve, in the present invention, so adjusts the counter-recoil orifice that a constant rate of fire is obtainable, whether the gun is being fired in a dive, during substantially horizontal flight, or when the aircraft is in a steep climb.

The present invention aims not only to provide for fulfilling actual requirements in an expeditious manner, but it aims also to provide a brake mechanism which is simple, light and relatively inexpensive, yet efiicient, desirable from numerous standpoints, and durable.

With the foregoing and minor objects in view, the invention resides in the novel subject matter hereinafter described and claimed, description being accomplished by reference to the accompanying drawings.

Figure 1 is a longitudinal sectional view partly in elevation showing the relation of the improved brake with the barrel, cradle, and recoil spring of an automatic cannon.

Figures 2 and 2A jointly disclose an enlarged longitudinal sectional view through the improved brake, the parts being shown in the positions which they occupy when the gun is in battery.

Figures 3 and 3A jointly disclose a longitudinal sectional view through the brake with the parts in the positions which they occupy substantially at the end of recoil.

Figure 4 is a fragmentary longitudinal section illustrating the position which the slidable buffer head or sleeve valve occupies during counterrecoil.

Figure 5 is a detail transverse sectional view on line 55 of Fig. 3 showing the gravity-actuated valve means which controls the counterrecoil throttling orifice.

Figure 6 is a fragmentary longitudinal section showing the position of the gravity-actuated valve when the gun is elevated. In connection with this valve and the same valve shown in preceding views, attention is invited to the fact that it is constructed for an automatic gun, for instance, for ground use, in which the barrel is not depressed below horizontal.

Figure 7 is a view similar to Fig. 6 but illustrating a gravity-actuated valve for use on guns carried by aircraft, which guns must be fired when depressed below horizontal.

Figure 8 is a disassembled perspective view showing the rear portion of the builer rod and the sleeve valve stops associated therewith.

Figure 9 is a detail elevation of the buffer head or sleeve valve and part of the bufier rod, showing a modification.

In the drawings above briefly described, features of construction have been illustrated which have been proven successful and advantageous from various standpoints, and while the structure illustrated will be rather specifically described, it is to be understood that within the scope of the invention as claimed, numerous variations may be made.

A gun barrel is shown at B, slidably mounted in a cradle C, said cradle having front and rear lugs F and R, which carry the improved hy draulic brake means H. A conventional recupei ator is associated with the barrel B and includes a counter-recoil spring S which returns the barrel B to battery after each recoil movement thereof. This barrel is provided with a gun lug G behind the rear cradle lug R.

Passing through openings in the lugs F and R; is a fixed cylinder flu. This cylinder, in the present disclosure, is held against rearward move-- ment by a sleeve H which is threaded upon the front portion of said cylinder and abuts the front cradle lug F, and said cylinder i held against plunger to occupy the space previously occupied by the buffer rod 29. Provision is made whereby this fluid may readily flow into the rear end of the plunger 2i upon the rearward or recoil movement thereof and whereby the fluid thus received in the rear port-ion of said plunger, may not escape therefrom back to the front portion of the plunger, as freely as it entered said rear portion, said escape, of course, occurring during counterrecoil of the barrel B and plunger 2 The means in question is preferably of the construction illustrated more particularly in Fig. 8 but shown also in a number of the other views, and is now forward movement by a ring nut 52 threaded upon the rear end of said cylinder and abutting the rear cradle lug R. The front end of the cylinder it is. closed. by a suitable head l3 having filling nipples I' l through which the hydraulic brake fluidmay be introducedinto said cylinder, and. it. may here be stated that the entire space within said cylinder not occupied by mechanical parts, is filled with said fluid, except for any slight space required to permit fluid expansion under temperature changes and under the heat of gun operation. Any leakage of fluid may, of course,. be offset by replenishing through the nip ples l but leakage is held to the minimum at all points. For this purpose, I have showna soft metal gasket l5 sealing the connection of the head l3- with the cylinder ill, and a similar gasket l6 sealing the connection of the ring nut H! with said cylinder. This ring nut carries an appropriate packing ll, wear on which may be compensated for by adjusting the gland E8. E9 merely denoted a locking screw for this gland.

Disposed axially within the cylinder Ill, is a buffer rod 26 whose front and. rear ends are denoted at 2 9 and 2d respectively, said rod preferably consisting of a major section 29? whose diameter gradually increases. rearwardly, a front section 26 which. is rigidly secured to the front cylinder head. if}, a rear section 2& and yet another section Ell which is interposed between and rigidly secured to said sections Zil and 28 A tubular brake plunger 2! is siid'ably telescoped with the cylinder El? and the buffer rod' Ell, said plunger 2| extending slidably through the packing means i'l, i8. and being suitably connected at 252 with the gun lug. G. This connection 22 may well be of the form shown by my U.. S.

Patent 1,447,087 of February 27, 1923, showing a coupling for the same purpose. A piston head 23 is provided on the front end of. they plunger 2|, said head having an external piston 2' 5 slidably engaging the cylinder id, and an internal piston 25, the inner diameter of which constitutes a throttling orifice cooperable with the red 29', the fluid-conducting space between said internal piston 25 and said rod it being at the maximum when the plunger 2| is at its extreme forward or battery position, said space, however, diminishing as the plunger moves rearwardly until it is finally closed, at the end of the recoil of said plunger and the barrel B. Upon the rearward or recoil movement of the tubular plunger 2|, fiuid around said tubular plunger, behind the piston head 23, finds its way into tubular plunger through openings 26 therein, and some of this fluid flows through the space between the int-erm1 piston head 25 and the buffer rod 2d,, while the rest of said fluid remains in said tubular described.

The section Zl'l of the buffer rod Ill) is formed with a plurality of large fluid-conducting grooves 2'! in its periphery, said grooves being spaced apart circumferentially of said section 28 The sleeve valve or buffer head 28 slidab-ly surrounds the rod section 26 and is of less length than the grooves 27. One stop 29 is provided on the rod section Zil tolimit the rearward movement of the sleeve valve 28, and another stop 39 is provided to limit the forward movement of said sleeve valve, said step 30 being preferably in the form of a rearwardly facing valve seat cooperable with the front end of said sleeve valve. Upon the recoil movement of the tubular plunger 2!, the fluid within the front portion of this plunger flows freely through the large grooves 27 under the sleeve valve 28 and enters the rear portion of said tubular plunger, said sleeve valve 28 being then in contact-with the rear stop 23 as seen in Figs. 3 and 3A. Upon the forward or counterrecoil movement of the tubular plunger 2!, the fluid which just entered the. rear portion of said plunger behind the sleeve valve 28, presses forwardly on said sleeve valve and engages it with the front stop or valve seat 36 as seen in Fig. 4. Restricted provision is made, however, to permit the fluid behind the sleeve valve 28 to forwardly escape past said sleeve valve, said restricted provision preferably consisting of clearance space 3| between said sleeve valve 28- and said plunger 2|. Thus, while the fluid behind the sleeve valve may forwardly escape to throttle the recoil movement of plunger 2| and barrel with the gun fired at substantially horizontal, said throttling would be too great to permit return of the barrel to battery against the action of gravity, when firing the gun in elevated positions. I, therefore, make novel provision whereby the fluid which enters the rear end of the tubular plunger 2! during recoil movement, may more freely escape when th gun barrel and the. brakemechanism are elevated above horizontal. This provision includes a fluid-conducting passage 32 extending longitudinally through the buffer rod- 26, the front portion of said passage being within the rod section 28 and the rear end of said passage within the rod section 26%. Said rear end: of the passage 32 is provided: with radial inlet ports 33 which extend therefrom through the periphery of said rod section 29 said ports .33: being so located that they will be closed by the sleeve valve 23 when the latter occupies. its rearmost position (gun recoiling) as seen in Figs. 3 and 3A. Upon counter-recoil, however, (Fig. 4) when the sleeve valve 28 moves forwardly, it uncovers the ports 33 and consequently they may receive fluid from the rear end of the plunger 2|; permitting the passage 32 to forwardl'yconduct this fluid into the front chamber 34 of the cylinder iii, if said passage 32 be then open'te said chamber. A gravity-actuated valve'means 35, located in the front chamber 34, however, controls communication between the passage 32 and said front chamber 34, and when the gun is fired in horizontal position or substantially in this position, said valve means 35 remains closed so that the proper braking of recoil movement will be effected by the brake plunger 2!, with the throttling afforded by the fluid-conducting passages thereof and the fluid passage 3| around the sleeve valve 28. This valve 35, however, automatically opens when the gun has been elevated above horizontal to a predetermined extent, and gradually opens more as the barrel is further elevated. Thus, with the barrel in such elevated positions that gravity acts seriously to retard the counter-recoil, the passage 32 in the rod 20 is gradually opened more and more into communication with the front chamber 34 of the cylinder Ill, so that the throttling action which would otherwise be produced, is materially lessened by free flow of fluid from the rear end of plunger 2| into the chamber 34, through the passage 32, during counter-recoil. It is thus insured that resistance to counter-recoil will be diminished as the gun is elevated from horizontal, and will be increased as said gun is lowered toward horizontal. The construction so far described will have its maximum throttling (gravity-actuated valve 35 closed) with the barrel horizontal and said valve will open only as the barrel is elevated (see Fig. 6). This form of construction is intended for guns to be used on the ground or other comparatively stable supports. When the gun is to be mounted on an aircraft, however, and it is essential said gun be depressed below horizontal, the valve 35 is of such form that it will be fully closed when the barrel is depressed to a predetermined extent below horizontal (Fig. 7). Then, the force of gravity aids counter-recoil of parts and it is of course for this reason that the brake mechanism exerts its maximum braking force. As the barrel is elevated, however, from the predetermined depressed position and gravity can no longer aid the parts during counter-recoil, the valve means 35 automatically opens so that the braking action during counterrecoil will be lessened more and more as the gun is elevated.

The valve means 35 is preferably of the con struction shown more particularly in Figs. 5, 6 and '7. From these views and others, it will be seen that the front extremity 32 of the fluid passage 32, turns upwardly and opens into a transverse bore 36, which bore is formed partially in two upstanding lugs 31 on the section 26 A cylindrical valve 38 is received in the bore 33 and is provided with at least one pendent weight 39, two weights being preferable. These weights are secured to the valve 38 and hold this valve in one position as the gun barrel is being raised and lowered. The valve 38 is formed with a transverse port 40 preferably in the form of a peripheral groove, and the length of this port may be disposed at any desired angle with respect to the vertical, to insure closing and opening of the valve 38 as required. In the form of the invention shown in most views, the valve 33 is fully closed when the barrel and the hydraulic brake mechanism H are both about horizontal, as shown in Figs. 3 and 3A, and as the gun is elevated, the port 43 gradually opens as will be clear from Fig. 6, until it is opened to the maximum at maximum gun elevation. As the gun is lowered from maximum elevated position, the valve 38 of course gradually closes. It will thus be seen that the gravity-actuated valve means 35 places the fluid passage 32 in more or less open communication with the front chamber 34 of the cylinder ID to automatically vary the braking action which the hydraulic means H creates to check the counter-recoil of the gun, the variance of the braking action being in accordance with the amount of gravity resistance which must be overcome in returning the gun to battery after recoil.

In Fig. 7, showing the valve means 35 for use on guns carried by aircraft, the valve member 38 must be so set with respect to the weight or weights 39 that said valve member will occupy a fully closed position when the gun barrel and associated parts are depressed to the maximum, the valve being partly opened when the barrel is elevated sufliciently to prevent gravity from assisting in returning the parts to battery and said valve being opened more and more as the gun is further elevated, automatically decreasing the braking action against counter-recoil as gravity ceases to assist this movement.

In the construction so far described, it will be recalled that the radial ports 33 at the rear end of the passage 32 (through rod 20) are closed by the buffer head or sleeve valve 23 when this part moves rearwardly upon recoil (see Fig. 3A). However, while this is preferred, it is not absolutely essential, and reference is now made to Fig. 9 in which ports 33 corresponding to the ports 33, open into portions of the grooves 27 instead of between said grooves.

As to more condensed explanation of operation, let it be recalled that Figs. 2 and 2A jointly show the normal relation of elements with the gun at rest and disposed horizontally, that is assuming that the gun be for ground use or have some application not requiring depression of the gun below horizontal. When the gun is fired and recoil occurs, the parts move as will be clear from Figs. 3 and 3A, some braking action being set up by passage of the fluid through the plunger ports 26 and the space between the internal piston 25 and the buffer rod 23 and some resistance being also caused by said internal piston forcing the fluid through the grooves 21 into the rear end of the tubular plunger 2!, the builer head or sleeve valve 28 being then in its rearmost position against the stop 29, as shown in Fig. 3A. The pressure of fluid of course moves the buffer head or sleeve valve 28 to this position from the forward position which it occupies in Fig. 2A. As soon as counter-recoil starts, the pressure of the fluid trapped in the rear portion of the tubular plunger 2|, slides the buffer head or sleeve valve 28 forwardly against the front stop 30. When this occurs, if the gun be substantially horizontal, the only way in which the trapped fluid may return from the rear portion of the plunger 2| to the front portion thereof, is through the restricted passage 3| around the buffer head or sleeve valve 28. A braking action is thus afforded here and also as the fluid must pass between the internal piston 25 and the buffer rod 20, additional braking action is caused here. If the gun occupy a sufficiently inclined position, during the recoil and counter-recoil movements so far explained, the gravity-actuated valve 35 will of course be open more or less. Consequent- 1y, some of the fluid from the rear portion of the plunger 2! may escape through the passage 32 into the front chamber 34 of the cylinder H), decreasing the braking action of the braking mechanism as required, according to the elevation of greater in connection with Fig. 7 than with the other views. Furthermore, in both forms of construction, as the gun is moved to a relatively elevated predetermined position, the valve 35 automatically opens, and as the extent of relative elevation increases, opening of the valve automatically increases. It is thus insured that theentire hydraulic brake mechanism shall resist'counter-recoil only to' a proper extent regardless of the position to which the gun may be vertically swung.

Attention is to be invited to the fact that the gravity-actuated valve 35 is mounted on apart (20 in the present disclosure) which is fixed to the cylinder l 6, which cylinder is in turn fixed to the gun cradle and has no recoiling or counterrecoiling movements. Consequently, recoil and counter-recoil will not seriously disturb the position of the valve member 38. Were it not for special provision, however, the surging of the fluid through the recoil orifice between piston 25 and rod 20 during recoil and counter-recoil would seriously affect this valve. To prevent this, I provide a shield 4! between the piston, 25 and the valve means 35 in which position it will protect said valve means against said surging fluid. This shield is preferably in the form of an annular flange carried by the rod section 251.

What is claimed is:

1. In a hydraulic gun barrel brake which swings vertically with the gun, a fixed fluid cylinder having a closed front end and an opening in its rear end, a buffer rod disposed longitud nally within said cylinder and secured to the front end thereof, a tubular plunger extending fluid-tightly through said opening and surrounding said buffer rod, said tubular plunger being spaced inwardly from the wall of said cylinder and spaced outwardly from said buffer rod, the front end of saidtubular plunger being provided with an external piston which contacts with said cylinder wall and divides said cylinder into front and rear fluid chambers, said front end of said tubular plunger being provided also with an internal piston spaced around said buiferrod to provide a throttling orifice, said tubular plunger having fluid-conducting means from its exterior to its interior, located behind said pistons, said fluid-conducting means having greater area than said throttling orifice; whereby during recoil the rearwardly moving external piston while creating a void in said front chamber will force fluid from said rear chamber through said fiuid-conducting means into said tubular plunger and some of this fluid will be forced from said tubular plunger through said throttling orifice into said front chamber to create a recoil-brakingaction; and during counter-recoil fluid will be forced from said tubular plunger through said throttling orifice into said front chamber and will be forced from said tubular plunger back through said conducting means into said rear chamber, to create a counter-recoil-brahing-ac tion; said buffer rod being provided with a longitudinal fluid passage extending from a point near the rear end of said rod to said front cham- W fluid tightly through said opening and surroundtion and for opening said passage when the barrel is elevated to a predetermined extent from said position.

2. In a hydraulic gun barrel brake which swings vertically with the gun, a fixed fluid cylinder having a, closed front end and an opening in its rear end, a buffer rod disposed longitudinally within said cylinder and secured to the front end thereof, a tubular plunger extending ing said buffer rod, said tubular plunger being spaced inwardly from the wall ofsaid cylinder and spaced outwardly from said buffer rod, the

front end of said tubular plunger being provided with an external piston which contacts with said cylinder wall and divides said cylinder into front and rear fluid chambers, said front end of said tubular plunger being provided also with an internal piston spaced around said buffer rod to provide a throttling orifice, said tubular plunger having fluid-conducting means from its exterior to its interior, located behind said pistons, said fiuidconducting means having greater area than said throttling orifice; whereby during recoil the rearwardly moving external piston while creating a Void in said front chamber will force fluid from said rear chamber through said fluid-conducting means into said tubular plunger and some of this fluid will be forced from said tubular plunger through said throttling orifice into said front chamber to create a recoil-brakingaction; and during counter-recoil fluid will be forced from said tubular plunger through said throttling orifice into said front chamber and will be forced from said tubular plunger back through said conducting means into said rear chamber, to create a counter-recoil-braking-ac tion; said buffer rod being provided with a 10ngitudinal fluid passage extending from a point near the rear end of said rod to said front chamher to forwardly conduct some of the fluid from said tubular plunger into said front chamber during said counter-recoil, to thereby decrease said counter-recoil-braking-action; and gravity-actuated valve means in said front chamber for closing said fluid passage when the gun barrel occupies a predetermined relatively depressed position, for opening said passage when the barrel is elevated to a predetermined extent from said depressed position and for opening said passage to a gradually increasing extent as said barrelis further elevated.

3. In a hydraulic gun barrel brake which swings vertically with the gun, a fixed fluid cylinder, a fixed rod and'a tubular brake plunger in said cylinder and so telescoped that said tubular plunger receives fluid upon barrel and plunger recoil and displaces the received fluid upon counter-recoil, said rod being provided with a longitudinal passage through whichsome of said displaced fluid may flow from said tubular plunger upon counter-recoil to decrease the braking action, fluid-actuated valve means within said tubular plunger and operative to admit fluid into said tubular plunger more freely upon recoil than the received fluid can be displaced from said tubular plunger during counter-recoil, and gravity-actuated valve means located without said tubular plunger for closing said fluid passage when the gun barrel occupies a predetermined relatively depressed position and for opening said passage when the barrel is elevated to a predetermined extent from said position.

4. In a hydraulic gun barrel brake which swings vertically with the gun, a fixed fluid cylinder, a fixed rod and a tubular brake plunger in said cylinder and so telescoped that said tubular plunger receives fluid upon barrel and plunger recoil and displaces the received fluid upon counter-recoil, said rod being provided with a longitudinal passage through which some of said displaced fluid may flow from said tubular plunger upon counter-recoil to decrease the braking action, fluid-actuated valve means within said tubular plunger and operative to admit fluid into said tubular plunger more freely upon recoil than the received fluid can be displaced from said tubular plunger during counter-recoil, and gravity-actuated valve means located without said tubular plunger for closing said fluid passage when the gun barrel occupies a predetermined relatively depressed position, for opening said passage when the barrel is elevated to a predetermined extent from said depressed position and for opening said passage to a gradually increasing extent as said barrel is further elevated.

5. In a hydraulic gun barrel brake which swings vertically with the gun, a fixed fluid cylinder, a fixed rod and a tubular brake plunger in said cylinder and so telescoped that said tubular plunger receives fluid upon barrel and plunger recoil and displaces the received fluid upon counter-recoil, said rod being provided with a longitudinal passage through which some of said displaced fluid may flow from said tubular plunger upon counter-recoil to decrease the braking action, gravity-actuated valve means for closing said fluid passage when the gun barrel occupies a predetermined relatively depressed position and for opening said passage when the barrel is elevated to a predetermined extent from said position, and additional valve means independent of said gravity-actuated valve means for closing said fluid passage during recoil of said plunger.

6. A structure as specified in claim 1; together with a fluid-actuated sleeve valve surrounding a portion of said rod within said tubular plunger and slidably engaged with said tubular plunger, said sleeve valve being slidable to one position upon recoil of said plunger and then permitting free flow of fluid into said tubular plunger, said sleeve valve being slidable in the other direction to a second position upon counter-recoil and then permitting only restricted return flow of fluid, one end of said fluid passage being located to be closed by said sleeve valve when said sleeve valve occupies said one position, said gravity-actuated valve means being located without said tubular plunger.

'7. In a hydraulic gun barrel brake which swings vertically with the gun, a fixed fluid cylinder having a closed front end and an opening in its rear end, a buffer rod disposed longitudinally within said cylinder and secured to the front end thereof, a tubular plunger extending fluidtightly through said opening and surrounding said buffer rod, said tubular plunger being spaced inwardly from the wall of said cylinder and spaced outwardly from said buffer rod, the front end of said tubular plunger being provided with an external piston which contacts with said cylinder wall and divides said cylinder into front and rear fluid chambers, said front end of said tubular plunger being provided also with an internal piston spaced around said buffer rod to provide a throttling orifice, said tubular plunger having fluid-conducting means from its exterior to its interior, located behind said pistons, said fluid-conducting means having greater area than said throttling orifice; whereby during recoil the rearwardly moving external piston while creating a void in said front chamber will force fluid from said rear chamber through said fluid-conducting means into said tubular plunger and some of this fluid will be forced from said tubular plunger through said throttling orifice into said front chamber to create a recoil-braking-action; and during counter-recoil fluid will be forced from said tubular plunger through said throttling orifice into said front chamber and will be forced from said tubular plunger back through said conducting means into said rear chamber, to create a oounter-recoil-braking-action; said buffer rod being provided with a longitudinal fluid passage extending from a point near the rear end of said rod to said front chamber to forwardly conduct some of the fluid from said tubular plunger into said front chamber during said counter-recoil, to thereby decrease said counter-recoil-brakingaction; and a valve for said fluid passage having a pendent operating weight in said front chamher for closing said valve as the gun barrel is depressed toward a predetermined position and for opening said valve as the barrel is elevated from said position.

8. In a hydraulic gun barrel brake which swings vertically with the gun, a fixed cylinder, fluid controlled means therein for braking recoil and counter-recoil movements of the gun barrel, said means including a recoil orifice and a fluid valve having a pendent operating weight located opposite said recoil orifice, and means mounted between said orifice and said weight to protect said weight against surging fluid from said orifice.

9. In a hydraulic gun barrel brake, a fixed fluid cylinder to swing vertically with the gun barrel, the front end of said cylinder being closed, a rod extending longitudinally within said cylinder and secured at its front end thereto, a tubular brake plunger entering said cylinder through the rear end thereof, said tubular plunger having means for connecting it with the gun barrel to recoil and counter-recoil therewith, said tubular plunger having an external piston dividing said cylinder into front and rear chambers which are in restricted communication with each other, said plunger also having an internal piston surrounding said rod, said rod being provided with a longitudinal fluid passage extending from its rear portion to said front chamber to forwardly conduct fluid, gravity-actuated valve means located in said front chamber for barring communication between said fluid passage and said front chamber when the gun barrel occupies a predetermined relatively depressed position and for establishing communication between said fluid passage and said front chamber when the gun barrel is elevated from said relatively depressed position, and fluid actuated valve means within said tubular plunger and operatively associated with said rod for freely admitting fluid from the front portion of said tubular plunger into the rear portion thereof during recoil of said tubular plunger and for restricting fluid return from said rear end of said plunger into said front end thereof during counter-recoil of said plunger, causing part of the fluid to then flow through said passage if said gravity-actuated valve means be then open.

10. In a hydraulic gun barrel brake which swings vertically with the gun, a fixed fluid cylinder having a closed front end and an opening in its rear end, a buffer rod disposed longitudinally within said cylinder and secured to the front end thereof, a tubular plunger extending fluid-tightly through said opening and surrounding said buffer rod, said tubular plunger being spaced inwardly from the Wall of said cylinder and spaced outwardly from said buffer rod, the front end of said tubular plunger being provided with an external piston which contacts with said cylinder wall and.

divides said cylinder into front and rear fluid chambers, said front end of said tubular plunger being provided also with an internal piston spaced around said buffer rod to provide a throttling orifice, said tubular plunger having fluid-conducting means from its exterior to its interior, located behind said pistons, said fluidconducting means having greater area than said throttling orifice; whereby during recoil the rearwardly moving external piston while creating a a void in said front chamber will force fluid from said rear chamber through said fluid-conducting means into said tubular plunger and some of this fluid will be forced from said tubular plunger through said throttling orifice into said front chamber to create a recoil-braking-action; and during counter-recoil fluid will be forced from said tubular plunger through said throttling orifice into said front chamber and Will be forced from said tubular plunger back through said conducting means into said rear chamber, to create a counter-recoil-braking-action; said buffer rod being provided with a longitudinal fluid passage extending from a point near the rear end ofsaid rod to said front chamber to forwardly conduct some of the fluid from said tubular plunger into said front chamber during said counter-recoil, to thereby decrease said counter-recoil-brakingaction; said rod being provided also with a transverse cylindrical bore across said passage, a cylindrical valve in said bore for controlling said fluid passage, and a pendent weight in said front chamber and secured to said valve for holding it in one position during elevation and depression of the gun barrel, said valve having a port eifec- .5

tive to open said fluid passage to a gradually increasing extent as the barrel is elevated from a predetermined relatively depressed position.

11.. In, a, hydraulic gun barrel brake, a fixed fluid cylinder to swing vertically with the gun barrel, the front end of said cylinder being closed, a rod extending longitudinally within said cylinder and secured at its front end thereto, a tubular brake plunger entering said cylinder through the rear end thereof, said tubular plunger having means for connecting it with the gun barrel to recoil and counter-recoil therewith, said tubular plunger having an external pistondividing said valve. during recoil.

cylinder into front and rear chambers whichv are in restricted communication with each other, said plunger also having an internal piston surrounding said rod, said rod being provided with a longitudinal fluid passage extending from its rear portion to. said front chamber to forwardly conduct fluid, gravity-actuated valve means located in said front chamber for barring communication between said fluid passage and said front chamber When the gun barrel occupies a predetermined relatively depressed position and for establishing gradually increasing communication between said fluid passage and said frontchamber as the gun barrel is'elevated from said relatively depressed position, and fluid-actuated valve means within said tubular plunger and operatively associated with said rod for freely admitting fluid from the front portion of said tubular plunger into the rear portion thereof during recoil of said tubular plunger and for restricting fluid return from said rear end of said plunger into said front end thereof during counter-recoil of said plunger, causing part of the fluid to then flow through said passage if said gravity-actuated valve means be then open.

12. A structure as specified in claim 9; said inner piston being spaced from said rod, and an annular flange onsaid rod between said inner piston and said gravity-actuated valve means shielding the latter against disturbance by the fluid surging forwardly between said inner piston and said rod.

13. In a hydraulic gun barrel brake, a fluid cylinder and a longitudinal rod secured therein, a tubular brake plunger so telescop ed with said rod and cylinder that said tubular plunger receives fluid upon barrel and plunger recoil and displaces the received fluid upon counter-recoil, a portion of said rod within said tubular plunger having a longitudinal fluid-conducting groove in its periphery to freely conduct said fluid into said tubular plunger during recoil, a sleeve valve slidably surrounding the grooved portion of said rod and of less length than said groove, said sleeve valve being slidable within said tubular plunger and being movable in one direction during recoil and in the other direction during counter-recoil, one stop for limiting the recoil movement of said sleeve valve to a position in which it will not close the adjacent end of said groove, and a second stop for limiting the counter-recoil movement of said sleeve valve, said sleeve valve when abutting said second stop closing the other end of said groove to prevent the fluid then being displaced from said tubular plunger from merely flowingfreely through said groove, restricted provision being made for conducting this fluid past said sleeve valve, said rod being provided with a longitudinal fluid passage having an inlet adjacent said longitudinal groove,

said inlet being closable by means of said sleeve- BRYAN P. JOYCE. 

